Free meals are offered to impoverished students in state-run schools as part of the government welfare measures in many of India's 29 states.
Authorities on Saturday said samples of cooking oil and leftover food taken from an Indian school where 23 children died after eating lunch this past week were contaminated with "very toxic" levels of an agricultural pesticide.
Ravindra Kumar, the additional director general of police in the city of Patna, told reporters on Saturday that forensic tests revealed that the samples contained the pesticide monocrotophos in levels that were "very toxic" for humans.
The free midday meal was served to the children on Tuesday in Gandamal village in Masrakh block, 80 kilometres north of Patna, the Bihar state capital.
Twenty-three children between the ages of five and 12 died from eating the meal and many others fell ill.
Meanwhile, school children have been dumping the meals they get as part of a school feeding scheme in fear of poisoning after the deaths.
Thousands of schoolchildren were refusing free meals in eastern India, officials said Thursday.
Authorities were trying to reassure frightened students and parents in the state of Bihar as police stepped up their investigation into the tragedy, focusing on the school headmistress who has fled.
Dumping their meals
The 23 children died after eating lentils, vegetables and rice cooked at a village school on Tuesday, sparking violent protests from angry residents.
Children elsewhere in the state were dumping their meals in bins or refusing even to touch them, despite pleas from school officials that the tragedy would not recur, a senior state government official said.
"Parents have warned their children to not even touch the meal served in the school," Lakshmanan, who uses only one name, told Agence France-Presse. – AFP; Sapa-AP